A numerical control device has been proposed for the conventional machining process of turning. The numerical control device includes a cutting-tool feed mechanism that feeds a cutting tool to a workpiece in at least two axial directions; and a control mechanism that controls the cutting-tool feed drive motor such that the cutting tool vibrates at a low frequency in at least two axial directions (see, for example, Patent Literature 1). In this numerical control device, the control mechanism includes an operation unit that performs various settings; a vibration-cutting-information storage unit that stores therein in advance at least the amount of forward movement, the amount of backward movement, the velocity of forward movement, and the velocity of backward movement of the cutting-tool feed mechanism according to mechanical characteristics, such as the inertia of the feed axis and motor characteristics, as a table of data used to synchronize and feed the cutting tool in at least two axial directions so as to be operable at a low frequency of 25 hertz or higher according to the rotational speed of the workpiece, or the amount of feeding of the cutting tool per revolution of the cutting tool, which are set by the operation unit; and a motor control unit that controls the cutting-tool feed drive motor on the basis of the data stored in the vibration-cutting-information storage unit.
Due to this configuration, in the case where a rotational speed of the workpiece, or an amount of feeding the cutting tool per revolution of the cutting tool, set by the operation unit, is present in the table, cutting work is performed by the amount of forward movement, the amount of backward movement, the speed of forward movement and that of backward movement of the cutting-tool feed mechanism corresponding to the set value. Further, in the case where a rotational speed of the workpiece or an amount of feeding the cutting tool per revolution of the cutting tool, which are set by the operation unit, is not present in the table, a warning that an appropriate value is not programmed is displayed, and processing is finished.
Another numerical control device for executing a contouring control by controlling two or more control axes for executing the contouring control has been proposed. The numerical control device simultaneously controls the two or more control axes to perform a chopping operation, and at the same time, generates movement data for executing the contouring control (see, for example, Patent Literature 2).